The seat Manning is vying for is currently held by Democrat Ben Cardin, who has held it since 2007.

Formerly a U.S. Army soldier assigned to be an intelligence analyst for the U.S. Department of Defense, Manning leaked classified military documents to WikiLeaks. She was subsequently convicted of violating the Espionage Act, among other charges, and sentenced to 35 years. After serving 7 years, her sentence was commuted by President Obama in 2017. Manning came out as a transgender woman in 2013.

After her release from prison, she moved to the suburbs in Maryland. According to her website, Maryland is her home state.